The present invention relates generally to the fabrication of a ring structure by low pressure plasma deposition processing. More specifically, it relates to the formation of a ring having alternating ferromagnetic and paramagnetic segments suitable for use in an aircraft generator.
Structures of ring configuration which have alternating segments of ferromagnetic and paramagnetic materials have been made heretofore. The use of such structures is in an aircraft engine generator. The magnet segments of the ring aid in supplying a needed magnetic field. The ring structure itself holds alternating permanent magnet wedges and filler material wedges in place within the ring and is mounted in the aircraft for rotation to bring the sequence of magnetic fields to a designated location as the ring is rotated.
In some designs of aircraft, permanent magnet aircraft generators require a segmented shrink ring which is comprised of alternating ferromagnetic and paramagnetic materials. The ring is mounted to the rotor for rotation with the rotor and to supply the magnetic flux as required in operation of the engine. Because of the high rotational speeds, the segmented shrink ring is required to reliably operate at stress levels of 130 ksi. This requirement places severe stress on the bonds between the ring segments. Presently, and prior art practice, these rings are fabricated by machining each of the segments and by then electron beam welding the individual segments together to form the ring of alternating ferromagnetic and paramagnetic segments. The welded structure is then given a finish machining and the alternating permanent magnet and filler material wedges are mounted in the ring to prepare it for mounting as a rotor of the aircraft.
This prior art fabrication method results in a successful segmented shrink ring but one which is very costly.